Frsed, rent have brmation i matflx

lar tem bnless, athe

ld quenched rtite, that I temperatures' rcsthat, after riloYs). IloY is heated pneous single- zurrounding r raPidlY cooled po without the kment than the e of martensrre t fhis leads to le time required lgrarn assumes

; matrix when crYstal structures' Problens 431 3*t- A groupof ferrousalloysa'uys ffiro*ion resistance. thattnat c,contain at least 1l% Cr,providing extraordinary martensite The I"to"* microconstituent---v'u!rruelrl ofor ftrernte tempered. and cemendteformed when martensiteis l::j,'"t::::i,,i'iJ:J:,:i"intn?.T,n"j:,n"provide combinations orhighhardness, tough- Vermiculargraphite Th rhis that tii,-i,',,,.is the ;'.J#:*j#iT:#::::1ji*hiteintendedshape rormsduring -i"'"^'r^"]"liuurcauonthe sori idification ductile:i:1,11*.last.jron. im compacted-graphite ofo1 iron. iron.rn, buthrrt itt- is a defectiveshape in White cast iron Castiro cementiterarher white irons n*Jl"i"il.i1lJ.produces than graphiteduring "* soridification.The

Section 13-l Designationsand Steefs Classificationof Section l3-2 SimpleHeat Treatments I3-l Whar is the differencebetween SectionI3_3 steels? cast iron and lsothermat Heatlreatments l3-7 Explain I3-2 what do the following heat Ar, At, A"^temperatures cess treatments:(a) pro_ Are ?nd refbrto? anneal,(b) thesetemperatures constant? normatizins,aiJ,St'#:i'fif;(c)annealine,(d) I3'3 Calculatethe amounrc of^r fe'ite'F---:.^ cementite' I mary microcorri,:'::-t: pri- 3'8 cttuent' and pearlite lowing in the iol- diagrams sbels: "?fii,:jtr..'jl^.1*:*"'*treatments "' only. (a) l3-g 1015 (b) 1035 In a pearlitic,,ttotn"*u' (c) 10e5 (d) 10r30 platelets 13-4 Estimate ate4 xto-' .Jt-o'"^1:tl'-'h:tftck, :t-totite the AISI-SAE and the ferrite .rlut.l.t, number for steelshaving arc 14 x f O_, the following microstructures: a spheroidl'"d steel,the ..rn.|'llt:o'In"rt toso lm peattite_62%o are 4 x to-3 \1! pnmary fenite it d;";.;.'u#:-"olttts cm 93% o/opii_"ry,.._.ri,, the total interface lb! pearlite_7 b.tw...r-tt" illi"lt area in a 1".! ??% feffite-3yocementrte centimeteror.uJtl-uTo*cementite cubic g6% Determinethe percent- @) ferite_!4?ocementite agereduction t, :.::::l areawhen the oearlitic l3-5 Completethe following steelis .ph..oidit*tuce table: 7.87 densityof ferrite is g/crnz rit-o^Jleol "ro cementiteis 7.66g/cm3, 13-10 Describethe mic 1035 steelafter.u.n in a 1050 t0l t5 ,rfltltulture,presentep tn the following Steet Steel ments: heat ffeat_ 41 temperature (a) 820"C,quench 43 or As^ temperature i^.::^., ro 650"C and hold ror 9Us, and quench Fullannealing to 25.C temperature (b) near at 920.C, t"tormalizing quenchr 450'c and temperature for eos, il;u.]ii|ro hold rrocessannealing (c) temperarure andquench tpneroidizingtemperature (d) f:]"1820.C, ro25"C 820"C,quench b 720.C rorl*1:, 100 andhotd 13-5 s,and quench to 25.C What do the terms low_, (e) medium_, and high- zzo"c carbon steelsmean? 1".,",,;l:ro::t'q,u;;;h"to ";1::.';j:andhord 500 ;"ffi". in:':-:s, and quench :1*:h,o ZSIC 13-4 Suenchand femperHeat Treatments 401

Primary x 100:36% -: HZ:ilL] (0.5- 0.0218 Pearlite: x 100:64ok I(0.77- 0.0218)il 3. Cool in air to room temperature,preserving the equilibrium amounts of primary ferrite and pearlite. The microstructureand hardnessare uniform becauseof the isothermalanneal.

Interruptingthe lsothermalTransformation Complicatedmicrostructures are pro- ducedby interrupting the isothermalheat treatment.For example,we could austenitize t the 1050steel (Figure 13-B)at 800"C,quench to 650"C and hold for 10 s (permitting I someferrite and pearliteto form), then quenchto 350'C and hold for I h (3600s). Whateverunstable austenite remained before quenching to 350'C transformsto bainite. d The flnal structureis ferrite, pearlite, and bainite. We could complicatethe treatment i- further by interrupting the treatment at 350'C after 1 min (60 s) and quenching.Any lr austeniteremaining after I min at 350'C forms martensite.The final structure now id contains ferrite, pearlite, bainite, and martensite. Note that each time we change the temperature,we start at zero time! In practice, temperaturescan not be changed of instantaneously(i.e., we cannotgo instantlyfrom 800to 650or 650to 350"C).This is f-.' ru why it is better to usethe continuouscooling transformation(CCT) diagrams.

900 Figurel3-8 Producingcomplicated structures by 800 interruptingthe isothermalheat --f"-z' 700 treatmentof a 1050 steer. 9 ooo I 500

b 400 Ferrite + pearlite+ bainite F :oo F 200 100 + bainite + 0 0.51 2 510 102 103 104 105 106 Time (s)

lx-4 0uenchandIemper l|eal Trentments

Quenching hardens most steels and tempering increases the toughness. This has been known for perhaps thousands of years. For example, a series of such heat treatments has been used for making Damascus steel and JapaneseSamurai swords. We can obtain an exceptionally fine dispersion of Fe3C and ferrite (known as tempered martensite) if .Suqcuonb eq pJno.^Aernlcn4soJcrru leq^\ relJ? .Euuedruelreu/Burqcuanbreru elrsuelJ€ru pue .olrur€q ,e1r1reed .elureg Bur (p) pue 'elruelsnepeur€ler (J) .Euueduel -ur€luoc eJnlcnrlsorcr{u (q) e seq (91-91 ern8rg) 'Surqcuenb(e) o/oz'0',(o1e-.uo1 :srrrretrFur,uoylo; eql qelOxg y1_g1 lFolsJ e ruo{ pecnpord ued y 51_91 sluouleelf esseupr€qqErq sql esn€c otr luorul€erl leog leaH laduel pue qf,uano .ggg ,_gI uorlsas eq1 ur 3uo:,u euo8 e,req lq8nu 1eq16 gH 0g ol punoJ sr sseupreg eq1 esoddns (J) .reolsqt eqlnuerls 0II0t (r) 080t(q) 0s0t (P) esnec o] luetuleoJl leeq eql ur Buor,r euo8 'rsd .1u0lu1€er1 e,req tq8rur 1eq16 000,gZI og ol punoJ sr 1e0r{eql Eurrnp IIlaorB pue uorleelrnu scrlour{ Ieels orllJo qt8uorls p1er.(1en1ce eqi osoddns (q) Jo eql uo Ieels egl Jo ]ueluoc uoqrec oq] 6luorulserl leeq Jo lco,ueerp ssncsrc 'J.009 s1ee1s snn ruo{ ur€}qo 01 lcedxe no,( p1no,u uo4e8 le 8ulro11oJerll peuue .,(1euueq1 o/o .qfuerls -osr ol permber serurl runrururtu -uolp pu? 'ssouprerl p1er,(1eq16 (e) eql eredruo3 g1-g1 '0S 'eurr1eleudordde ue ro.; CUH gtl^{ Ieotsgggl peredurelsneue (l) 3"00t 1Bpersdutel pve,J.gZ ol Iro ur peqcuenb 'J"028 pezDluolsne 'sg rllp\ w eq ppoqs Ieels 0g0I v gI-gI cuH Ieersg1lgy peredur.rrrrnoll,", '0t JUH qtr^{ Ieotsgggy pereduretrsn€u€ (p) ;pueuruocer no,{ '8€ plno,^a eJnleJedurel Eurzrlruolsne 3UH l€qdypesn qlp\ Ioels pal€ouue ,(11euteq1osr s3,&\ 0g0l ue (J) l3q1 e;nleredurel 8urzrlruelsne oql pu€ olrs '0r -uou?ru .elrr JdH orJlJo lueluoc uoqJec oql olelurlsg qll& peleeuue oh1V Ieols0II0I flprureql0$ u" (q) -leJ pu€ elrsuelr€ru %09 Jo pesodruoc e;n1 ,1ueu4eer1 '€z Jl{H -cnrtrs Ieug e Surcnpord redurel leeq ql}^\ Ieels 0g0I pepeuue .{lyeuueqlosrue (e) pue qcuenb redordrur ue ue.r.r8sr Ieols 0[0] V ZI_SI :seurl pu€ sernleredureleteud ,Bur,tro1Jo.; 6peleouue ero,r 1rJr Ioels -o.rdduSurpnpur orll utetqool sluoru oql w pour€lqo 0S0l 0q p1no,r uorleEuole 7 -leorl leoq IeruJer{}osrelerrdordde puorutuoce11 .q18uer1s ZI_SI I pue 'q13uer1s epsuel p1er,( leq16 (3) ol pue ,s aluerulBeJl leeq erues J.gZ loor 009t roJ 01 .f,.92 .s eqt .{q 1ee1s0g0l e ur peure}qo eg ppo.r J.09t teeq ol qcuenb 00I roJ * ploq pue 01 qcuenb.J.006 I{13uer1s olrsuet pue qtEuerls pyer.{ 1eq16 (q) C"008 o] teeq (q) 'lueruleorl ol : leeq sql ,(q peurelgo eJe lerll J.SZ IoocJIe pue 's roJ qfuerls p1er,( pue 'uo4e8uole 0/0 ,requmu €01 ploq pue J.00€ 01qcuenb 's 1 rog .pe^oryce ploq pu€ ot qcuenb,C.006 sseupr€rl [eurrg eql euruilelecl eq J"919 ol leeq (B) ,sernle.redurel 01 sql slruued 1eq1 eleudord J.SZ ol 1ooc,(1,tro1spue 's roJ ploq ,s -de Sulpnlcur 'tuor.uleertleeq e pueuuoreu 006 pue J"00? ol qcuenb I roJ (e) pJoq .C"006 pue J"SL7 ol qcuenb or teeq (J) '%09 lseel le 30r€ ur uorl ,s Jo J"gZ ol qcuenbpu€ I roJ -cnper e pue rsd 000,9/l tseel treJo ql8ue4s elrs ,O.006 ploq pu€ J"SL9 ot qcuenb o1 t€oq (e) -uel u seq leql loels 0g0I e ecnpord o1 qsr,l.eA\ ,s 9I_gI J.SZ ol qcuenbpue 002 roJ ploq pu€ ,J.006 eJeA\ J.00t ol qcuenb ot leeq (p) epezqeuuou lrJr Joels ,C"006 0S0I oqt ur pourelqo 0q plno.r\ uorle8uole )"gZ ot qcuenbpu€ 01]eoq (f,) ,s o7opue qlSuetls olrsuol ,q13uer1splerf J.SZ ol qcuenbpue 0SroJ 1eq16 1r) ploq ,C.006 pue J.009 01 qcuenb o1 teorl (q) ;lu0r.ule0Jl .s t€eq erues eqt .{q e ur peurelqo C.SZ01 qcuenb pue roJ lee1s 0g0I .C"006 €01 oq plno,$ qt8uorts ploq puu J.00t ot qcuenb ot (B) elrsuot pu8 p1er.{ 1eq16 1q; leeq ']uorul€oJl leerl slu0ur srql dq peurelqo or€ treql rJl8ueJlselrsuel pue -leerl lperl 8ur.tro11ogeq1 ur dels qceerolJe .po^orqce Ieols ql8uerls p1er.{eql ouruuelecl oq ot 0lI0I e ur lueserdernlcrulsorcnu (soJnleJeduel erll eqrrcseqII_gI srql slruJed l€ql eleudordde ot rr3 pue ,s Eurpnlcur '1ueru1eer1leoq e pueururoced (e) J"gz looc €0I roJploq pue Co00901 teeq '3"97 o1qcuenb ,J.gZg '%gI le teeq 6) lseel le Jo ol qcuenb uorleEuole J"gZ Puu ue pue gfg ts€ol le Jo sseupreq '.s ,s IIou 0I roJ ploq pu" J"00t ot qcuenb 00I roJ -rrg e seq 1€rll Ieels 0g0I e ecnpord o1 qsr.tr o,45 gI_tI ,J.Oeg ploq pue J.\CL ot qcuenb te leeq (I)

suoJl pue lseS sloelsl0luoulestl lesH gt ulldvHC ztn Problens 433

obtained if we useda 1080steel? What micro- 13-25 A steelpart must havean as-quenched structurewould be obtained hardness if we used a 4340 of HRC 35 in order steel? to avoid excessive_wear rates during use. When the part is made from 900 4320steel, the hardnessis only HRC 32. Deter- mine the hardnessif the part were made under 800 identical conditions, but with the followrns 700 steels.Which, if any, of thesesteels would bi betterchoices than 4320? U 600 (a) 4340 (b) 8640 (c) 9310 E 500 (d) l0s0 (e) 1080 400' 13-26 A part producedfrom a 4320 steelhas a hard_ ness of HRC 35 F 300l at a critical location after quenching.Determine 200 (a) the cooling rate atthat location. and (b) 100 the microstructureand hardnessthat would 0 be obtainedif the part weremade of a l0g0 1 steel. 13-27 A 1080steel is cooled at the fastestpossible Figurel3-15 (Repeatedfor problem13-19.) The rate that still permits all pearlite to form. What CCTdiagram for a low-alloy,O.zyo C steel. is this cooling rate?What Jominy distance,and hardnessare expectedfor this cooling rate? 13-20 Fine pearlite and a small amount of marren_ 13-28 Determine the hardnessand site are found in a quenched10g0 steel.What microstructureat the centerof a 1.5-in._diameterl0g0 microstructurewould be expectedif we used a steelbar producedby quenching low-alloy, 0.2% C steel?What microstrucrure in would be expectedif we useda 4340steel? (a) unagitatedoil, (b) unagitatedwater, and (c) agitatedbrine. Section 13-5 Effect of Altoying Elements 13-29 A 2-in.-diameterbar of 4320 steel is to have Section 13-6 Application of Hardenability a hardnessof at least HRC 35. What is the 13-21 Explain the difference between hardenability minimum severityof the quench(H coefficient)? and hardness.Explain usinga sketchhow hard_ What type of quenching medium would you enability of steelsis measured. recommend to produce the desired hardness with the leastchance of quenchcracking? 13-22 We have found that a 1070steel, when austeni_ tized at 750"C, forms a structure containins 13-30 A steelbar is to be quenchedin agitatedwater. pearlite and a small amount of grain_boundar! Determine the maximum diameter of the bar ferrite that givesacceptable strength and ductil_ that will producea minimum hardnessof HRC ity. What changesin the microstructure,if any, 40 if the bar is: would be expectedifthe 1070steel contained an (a) 1050 (b) 1080 (c) 4320 alloying elementsuch as Mo or Cr? Explain. (d) 8640 (e) 4340 13-23 Using the TTT diagrams,compare the harden_ 13-31 The centerof a 1-in.-diameterbar of 4320steel abilities of 4340and 1050steels by determining has a hardness of HRC 40. Determine the the times required for the isothermal transfor_ hardnessand microstructureat the center of a mation of ferrite and pearlite (F", p", and &) to 2-it. bar of 1050 steel quenchedin the same occurat 650"C. medium. 13-24 We would like to obtain a hardnessof HRC 3g to 40 in a quenchedsteel. What rangeof cooling Section 13-7 Speciatty Steels rateswould we have to obtain for the following steels?Are somesteels inappropriate for achiev_ Section 13-8 Surface Treatments ing theselevels ofhardness? Section 13-9 Wetdabitity of Steel (a) 4340 (b) 8640 (c) 9310 13-32 What is the principle of the surface (d) 4320 (e) 1050 (f) 1080 hardeninsof steelsusing carburizing and nitriding? eul (JeAo.r\oH.ec€Jns Jo reluoc oql eql 'uI Ioels Jo ,(q16 ;.royreqeqcrleu8eru 9Z'0 ulqlp\ g€ cl{H peecxeppoq. eq1Fursnec sr lcedxe ,r.uprnq no,( ppo,n eseqd ,t(q)SZ_gi eq1 'e1e1dreo,r eql go luerueceldr, 1eq.tr ,"ili;;;; 1.rr.,b.ri ."ueuauu, prolu oJ 'lrun Eurqsruc_{Jolp .rog ;:]l_:_t-",tdJ--tN-rJ-ol or{} uo poseg e1e1d.ree,i ag ,(uu ysodo Ieels >lcrql-'ur-ge ecnpo:d 01 o{{ plno^t ^llqbrls el6 gr_tl 1,.,,,,,pL,,;;J;il;t JffJ?,,ffjJ,'#"Joa_er epeuuoJsoseqd urnuqrpnbe eql plun peredual- ueql oro.r{elrsueuetu oW jr pecnp -otd eq plnod\ .qcuentr ornlcrulsoJcru1eqr16 eq1 nod Suunp elrsuelreru 6ppe lsntu uocrlrsJo e8eluecred 1eq,u %001 ulelqo ol sn lruued '%t't^sl uorl orll ur .orr plnoA\lEql ernleledurel lurluoJ uoqrpJ oql .tI Euzrlruelsnepue luol -qde.rE -uoc uoqrec .rJ .lo olruolsnB,{lewud ou qll.r ,"rraa'rnq, e puoruruocol{ yoLI Burureluoc Surlsecuor der8 e ecnpord IoelssseJurels cnrsueperu e ecnpord or orttt ptr,oni".i oo-rf 01 rIsJ.&elA 6t-gl arsq lsel orltrJo releuerp eql sl sleerssseJur€rs {uFIl no,( op leql6 erogurnuss"lc eql fq ue.trb ere,q16 aroels sseluretrs ueqt ,r-r, leql re1ee.r8{fuerls olrsuel eqt ,i dqrvf "tXttjlJJli 'Isd slsolsssalurels oI-gI uotlJes 000'0S;o ql8uerls olrsuelB .nnq o1 p*o3 sr Surlsecuor der8 sselc 0, s Jo req elrsuelV t?_EI 8Z CUH Luru0z'0 esuolrlsec sed.{1 ";,'':lJTlilT ZTCUH so ,"J:;# .r-r, urLUEI"0 O' 3UH u.il-u0I 0 -erpeseqd eq1 09 CUH ururg0'0 J€ec-a.{ Bursnuorr ls€c ,ffif, ,o_r, suoll lse3IT-tI uotlJas pls/tl euozuotsnj 090t ul sseuprBH l0 eipl- tuotlocuelsl0 uloor alqels rslueluoJ -'ajnleradueJ lp staltualsne 1' uoqleJ-iv\oliv 'lN %grc 731 luelsuocn 1' ,"ran,p 'lools pople^\_se 9:9y9uoqrec-lelJ|u-unruorqc_uo.il aql ro,1"r, 0g0l oql ur uo4ecol (q)(gt-tI Jo qreo re emlcn,lsorcr.'' eqr .r,ro4ipuo" :* V uatqordro,r paleedag; eZlet eiffiu lclpord otueseql repun peple.&ere.tr loetrs0g0t e i iutod (q) qJBJ l3 pelredxe sessouplpr{ oql euruuelerT J' 'auoz uotsnJeql uoqJecluecred lr{81e16 Jo e8pe oqr uo{ ,uo,tnro] ") snorre^le pour€lqoerB orrozpr1".gn_1nrq €'0 .Burlooc ui z'0 sesseupr€rl roUV .pople^\ "q1 111r"1. gggl V lg-gl uoqrec-q8rq .rele 1,sloels plemot llncsrp sr 1r -rrroq's1ee1s uoqJ€c-.roJ pJe.r\ ol Jers€o1r sr fq16 9g-g1 ,elruelsne eosecsrql ur pour€treJJoeJoJ eql st lpq^\ asleelsuoqJBJ-^\oJ roJ.Ioq8rq sr euoz pelco,Ue-teeqeq1 go qfuerls 'J orlt luql i1-srfqrq gg_g1 tso o -Inseslruo{sle^roru,"li;:iT}',,i,l,],,',"""j - -olJltlt pue sseqdqrea3o tunouu 'dutztrnqluJ Jr.[]eururJeleD nt reue pelooc,(1mo;s sr 'I00ls 1..1, .q1 jj eqlJo oc€J'nsoql ruo{ ecuetrsrp.ql.nrr"i 000I uoqrec luec;ed oql .leols lold oql Jo eceJmseqtr W ol)Z'I J secnpotd1eq1 eJeqdsourle se8-e Bursn rI z roJJ"0901 ]e pezrmqrEroq ol sl Ieolssl0I V e roJ g reldeq3 .ur 't_tl I ,,",^_ ee5) 16.91o qrqepesur^^!l:,nor u ocnpord 01 perrnber .J"0001 .*,1 .rliiu* ruop .l 00sr .retop le srBurzunq;ec-l y"i.o ls€el r€ sureruocrerll ecerns orll aoloq ,"unirlp eql s€ peugop s1 qldep esec orll .1".1, eror^eqoqc4euEeuruou oql erolsor01 op go no,,{- oc€Jrnseql rc J o secnpord "q1 pJnoc}erli11 apeuuoJ eaeq eseqd srql 0.I 1eq1ereqdsour]n lq8ru se8 e Eursnpezrrnqrec eq 01 sr loels 0I0I v gg_tl

suojllsec pueslools lo luauleotl lpaH el ulldvHx vtb Problens 435

plate should have a hardnessof no more than t3-46 A quenchedand tempered10110 steel is fbund HRC 32 to assuresome toughness.We have to have surface cracks that cause the only a water quenchavailable to us. Desien heat_ the treatedpart to be rejectedby the plate,assuming that we only customer.Why have the steels did the cracks form? givenin Figure Design a heat trearment, 13-21available to us. including appropriate temperaturesand times that will minimize theseproblems. 13-47 Design a corrosion-resistantsteel to use for a pump that transportsliquid helium (He) at 4 K rn a superconductingmagnet. 13-48 Design a heat treatment for a hook made of l-in.-diameter steel rod having a microstruc_ ture containing a mixture of ferrite, bainite, and martensite after quenching.Estimate the mechanicalproperties of your hook. 13-49 Designan annealingtreatment for a 1050steel. Be sureto include detailsof temperatures,cool_ ing rates,microstructures, and properties. 13-50 Designa processto producea 0.5_cm-diameter steelshaft having excellenttoughness, yet excel_ lent wear and fatigue resistance.The surface hardness shouldbe at leastHRC 60, and the ulu20 hardness 0.01 cm beneaththe surfaceshould be Jominydisrance (rtth of aninchl approximately HRC 50. Describe the process, including details of the heat_treatins atmo_ Figure13-21 (Repeatedfor problem13_45.) The sphere,the composition of the nardenabtlttycurves for severalsteels. steel, iempera_ tures,and times.